1. Field
The present work relates generally to wireless communication and, more particularly, to channel estimation in Orthogonal Frequency Division Multiplexed (OFDM) communication.
2. Background
Conventional OFDM communication links that operate at high mobility (high Doppler spread) typically use scattered pilots. When the link is subject to high mobility and high delay spread the estimation of the channel transfer function at each OFDM symbol at each carrier is one of the main challenges. The scattered pilots in each symbol may be seen as frequency samples of the “true” FT (Fourier Transform) of the Channel Impulse Response (CIR). The prior art uses 2-D (time and frequency domains) interpolation techniques to interpolate the known scattered pilots. If, however, within a single OFDM symbol, the scattered pilots are evenly distributed but with a sampling rate that is too low, this causes ambiguity in the CIR reconstruction for high delay spread situations. More specifically, for cases of high Doppler and high delay spread, inaccuracy in time domain interpolation causes a problem with CIR estimation inaccuracy, referred to as aliasing. This aliasing phenomenon limits the performance of the existing solutions.